I would consult your mom on the matter. She is a good friend to her and can tell you what she thinks on this matter. Tell her what you wrote in the OP about why not and see what she says.

This situation is pretty complicated by my parents. For a lot of complicated reasons to do with small town politics, my immigrant mom's social attitudes, and a teensy dash of moral cowardice, both of my parents would really, really prefer I not rock the boat with this. Their mindset is more "Obviously the socially prominent Hector should be at our party: otherwise people might gossip about his exclusion and/or have hurt feelings."

Hortense is more realistic about the whole thing. If she weren't a divorce-opposing Catholic, they would've split up years earlier. She realizes he's beyond a boor.

Who is hosting the party? Your parents or you and Partner? If your parents are hosting, I think they can invite both Hector and Hortense as it would be their "social standing" that would be affected by not inviting them. Your father could try and corral Hector and keep him near the men talking about "guy things" but I doubt this would work. You may just have to deal with it (as much as I hate saying that).

If you and Partner are hosting, I think you have more leeway to not invite either. I know that etiquette says that you must invite both halves of a social unit, but I think since you don't live in the area you could get away with only inviting Hortense. Of course, there may be people that will think and gossip about how rude you are once the party is over.

I would not have Hector at a party I hosted or where I was the guest of honor. That would be my hill to die on. However, Hortense herself isn't my hill. So I would leave that part up to your mother, as a compromise. If, to make her happy, Hortense should be invited solo, I would be willing to bend etiquette. If she prefers that Hortense not be invited solo, then she is the one to deal with the fall out.

Is there no etiquette rule that allows us to omit a guest who is guaranteed to make half the guests uncomfortable? Why is his comfort or "image" more important than the hosts" or the other female guests'?

This is not just about the engagement party. Since Hortense is such a good friend to the OP's mom, there's a very good chance that Mom will want Hortense invited to the wedding. And in many places, an invitation to the engagement party more or less means an invitation to the wedding. And I think whatever the OP does for one, she should do for the other.

I'd go with not inviting Hortense or her husband. The social pressure to invite both halves of a couple has allowed this man to continue to behave inappropriately. If Hortense chooses to remain in a relationship with him, she should expect to reap the results of that. (Catholics I know who won't get divorced do get separated and live separate lives. Hortense does have choices.)

Is there no etiquette rule that allows us to omit a guest who is guaranteed to make half the guests uncomfortable? Why is his comfort or "image" more important than the hosts" or the other female guests'?

The host makes the guest list - that's the rule that lets her leave him off. But that rule is tempered by the spousal unit rule. She can leave this couple off altogether, but doesn't want the natural consequences of doing so. There is no etiquette rule that magically gives us what we want with no negatives.

The reason why these rules are in place is to protect the general way of things, and yes, in specific unusual situations, it can be a hindrance. However, picking and choosing where to apply the rules is one quick way to messing up the whole system. This is what keeps upset MILs from excluding their DILs from family events, resentful friends keeping the new fiance from attending the annual couples' getaway, and spiteful neighbors from excluding the spouse who puts up better Christmas lights from their Holiday party.

I think this case is particularly difficult because everyone else seems to enjoy the wife enough that they are well liked and respected members of the community. Also it looks like no one knows how to deal with a lech. the thinly veiled sexual jokes you don't laugh at and you don't ignore you a little loudly play dumb " why what every do you mean, I'm afraid I'm not following you? My husband cant keep up with me ?"

Hector basically cannot leave the house without sexually harassing at least three girls/women. A lot of what he says could sound innocuous coming from other people. He doesn't leap out of bushes or molest children or anything quite so... dramatic. But he does make girls and women feel really gross. He makes me feel really gross, in fact. He's been doing so since I was a tween. I do not tolerate his behavior, and I avoid being at events where he is.

Hector is a perv. A well-known perv from the sounds of it. Is this a case where safety trumps etiquette? I certainly wouldn't invite someone who harasses/molests women to a party, regardless of the "couples rule"!

Since Hortense know's her husband is such a bore, does she attend events and socialize without him?

My parent's had a friend, Eve, who was married to a jerk. For social, property, family and a whole lot of pig headedness, Eve would not divorce her DH. I literally have no memory of Eve not being in my parents social circle and she even gave a Eulogy at my Dad's funeral. I never met her husband, even though we lived in a relatively small town. She lived her life separately, so inviting Eve without her husband was quit common and acceptable.

We had a friend in our neighborhood who was married to an alcoholic. Any event he attended ended up with a major scene. My friend did not believe in divorce and she was able to eventually get him into counseling and he's been sober for several years. But for those 5 years, friend was invited and her DH wasn't.

So in my experience there are some situations where traditional etiquette rules can be broken without any major fallout.

On the other hand, if it is a small town, most guests will be used to his antics and will ignore him. You can worn guests unfamiliar with him and recommend they stay away from him. And if your SIL has the guts get her to respond to him with "Oh, YOU must be the dirty old man OP warned me about."

My partner and I are planning a party to announce our engagement in my hometown: a low key, cheerful celebration focused on reconnecting with old friends and relatives.

Note the strikeout above. that is my first suggestion. If you change make the engagement party about family only, then you no longer have to worry about the Hortense/"couples rule" issue.

Bah, humbug. It's bad enough to have a party which someone I genuinely like cannot attend because of a lamentable choice she made at 19 without also excluding my beloved third grade teacher and my parents' pastor and my best friend's sweet mum.

My partner and I are planning a party to announce our engagement in my hometown: a low key, cheerful celebration focused on reconnecting with old friends and relatives.

Note the strikeout above. that is my first suggestion. If you change make the engagement party about family only, then you no longer have to worry about the Hortense/"couples rule" issue.

Bah, humbug. It's bad enough to have a party which someone I genuinely like cannot attend because of a lamentable choice she made at 19 without also excluding my beloved third grade teacher and my parents' pastor and my best friend's sweet mum.

Well... then just don't invite Hortense/Hector.

Or invite only Hortense. (I honestly believe that Hectors perverted/harassing behavior is a legitimate reason to exclude him despite the couple's rule)

Or tell your Mom that you refuse to attend a party where Hector is present and let her decide if she wants to invite Hortense only, or exclude both of them.

Really, a PP put it best. You can't make everyone here happy. Not gonna happen. Someone is going to end up being unhappy, no matter what you decide to do.

So you need to decide who's feelings matter the most. Who do you want to be happy?You and your fiancee?Your parents?Hortense?Hector?Your other guests?

My partner and I are planning a party to announce our engagement in my hometown: a low key, cheerful celebration focused on reconnecting with old friends and relatives.

Note the strikeout above. that is my first suggestion. If you change make the engagement party about family only, then you no longer have to worry about the Hortense/"couples rule" issue.

Bah, humbug. It's bad enough to have a party which someone I genuinely like cannot attend because of a lamentable choice she made at 19 without also excluding my beloved third grade teacher and my parents' pastor and my best friend's sweet mum.

Well... then just don't invite Hortense/Hector.

Or invite only Hortense. (I honestly believe that Hectors perverted/harassing behavior is a legitimate reason to exclude him despite the couple's rule)

Or tell your Mom that you refuse to attend a party where Hector is present and let her decide if she wants to invite Hortense only, or exclude both of them.[/u]

Really, a PP put it best. You can't make everyone here happy. Not gonna happen. Someone is going to end up being unhappy, no matter what you decide to do.

So you need to decide who's feelings matter the most. Who do you want to be happy?You and your fiancee?Your parents?Hortense?Hector?Your other guests?

The problem with the "babysitter" or flyswatter ideas, much as they appeal to me, is that often guys like this aren't doing anything so overt that most people would feel comfortable saying "Hey, knock it off!" These guys operate at that 'just under the line' place so any one comment, taken in exclusion, isn't so bad. And most people are just not going to feel ok telling someone off for something that, when described later, will sound 'complimentary'. "Why did you need to make a scene, he just complimented how you looked in that new sweater!" without being aware of the gross looks and overall creepiness.

I know guys like this, unfortunately. Since they aren't actually *doing* anything, it is really really hard to pin them down. even telling them to stop doesn't work, because it's 'stop what?' and pretending to be all hurt and confused.

I was on the receiving end of this crap some years ago... in a work situation, which is a real sticky wicket. I remember someone saying something that creeped me out (It was the tone more than the actual words) and I replied "Excuse me, Mr [name redacted]?" in that tone that suffers no fools at all. That stopped him for that occasion.

My boss was a man who had no sisters and no understanding of what this was about. It took six women from the office to tell stories about this creep before he was willing to observe and tell him off. This may require something similar in this case if the OP is forced to permit Hector to attend the engagement party and/or the wedding.

If that is the case I vote for hiring someone to do this rather than assigning this duty to a friend.